title: A delta 4-3-keto pathway for testosterone synthesis in the human spermatozoa.
abstract: The ability of human spermatozoa to metabolize pregnenolone to progesterone and progesterone to testosterone was assessed. Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32-38 years; n = 6, age 30-51 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5, 100.1 and 248.8 millions per ejaculate, were separately incubated with [7n-3H]pregnenolone and [1,2,6,7,16,17-3H]progesterone. Using the classical reverse-isotope dilution technique the desired products [3H]progesterone and [3H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.4 to 12.2% and 3.1 x 10(-2) to 2.0 x 10(-1)%. Such metabolites were not evident in the controls. The results indicate that the human spermatozoa contain the enzymes necessary for the transformation of pregnenolone to testosterone via the delta 4-3-keto route.
authors.affiliation: University Department of Obstetrics & Gynaecology, National University Hospital, Singapore.
authors.forename: R
authors.initials: R
authors.lastname: Gunasegaram
authors.forename: P C
authors.initials: PC
authors.lastname: Chew
authors.forename: A
authors.initials: A
authors.lastname: Loganath
authors.forename: K L
authors.initials: KL
authors.lastname: Peh
authors.forename: S S
authors.initials: SS
authors.lastname: Ratnam
mesh_terms: D000328:Adult; D002855:Chromatography, Thin Layer; D006801:Humans; D066298:In Vitro Techniques; D007248:Infertility, Male / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011284:Pregnenolone / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D011865:Radioisotope Dilution Technique; D013076:Sperm Count; D013094:Spermatozoa / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D013739:Testosterone; D011374:Progesterone; D011284:Pregnenolone